Bacillus subtilis B55 degraded the ferulic acid and p-coumaric acid and changed the soil bacterial community in soils.

Aims: This study aimed to assess the effects of phenolic acid-degrading bacteria strains on phenolic acid content, plant growth, and soil bacterial community in phenolic acid-treated soils.

Methods and results: The strain of interest coded as B55 was isolated from cucumber root litter, and its degradation rates of ferulic acid and p-coumaric acid were 81.92% and 72.41% in Luria-Bertani solution, respectively, and B55 was identified as Bacillus subtilis. B55 had plant growth-promoting attributes, including solubilization of inorganic phosphate and production of siderophore and indole acetic acid. Both ferulic acid and p-coumaric acid significantly restrained an increase in cucumber seedling dry biomass, while the B55 inoculation not only completely counteracted the damage of phenolic acids to cucumber seedlings and decreased the content of ferulic acid and p-coumaric acid in soil, but also promoted cucumber seedlings growth. Amplicon sequencing found that B55 inoculation changed the cucumber rhizosphere bacterial community structure and promoted the enrichment of certain bacteria, such as Pseudomonas, Arthrobacter, Bacillus, Flavobacterium, Streptomyces, and Comamonas.

Conclusions: B55 not only promoted cucumber seedling growth, and decreased the content of ferulic acid and p-coumaric acid in soil, but it also increased the relative abundance of beneficial microorganisms in the cucumber rhizosphere.